Quantum Operations in Transmon Qubits Using Superconducting Digital Electronics

We present a method for bipolar pulse control of transmon qubits based on superconducting digital electronics. To synthesize high-fidelity quantum operations, robust optimization algorithms (gradient descent, genetic algorithms, and machine learning approaches) were developed to minimize leakage of the qubit state out of the computational subspace. Quantum operations with a fidelity of 99.99% were demonstrated using sequences of single flux quantum (SFQ) pulses. A key advantage of our approach is the two-fold reduction in the single-qubit gate time compared to conventional unipolar SFQ control. The prospects of this technology for scaling quantum processors are also discussed, including the reduction in the number of control lines, minimized noise, and the potential for multiplexing control of multi-qubit registers.